We show that the Cabibbo angle theta\_c satisfies the relation tan(2
theta\_c)=-+/- 1/2 when universality for diagonal neutral currents of mass
eigenstates is satisfied at the same level of accuracy as the absence of their
off-diagonal counterparts. The predicted value is cos theta\_c \approx 0.9732,
only 7/10000 away from experimental results. No mass ratio appears in the
calculation. theta\_c occurs a priori for both quark species, and, showing that
one recovers the standard dependence of leptonic and semi-leptonic decays of
pseudoscalar mesons, we advocate, like for neutrinos and charged leptons, for a
symmetrical treatment of u and d-type quarks.Comment: The Cabibbo angle can be positive or negative, which was overlooked
in the first version. Minor addend